Human beings can only see around 30 shades of gray, according to a bit of trivia Popular Science says it found in a research paper and has decided to share "for no particular reason whatsoever." The exact number of shades of gray we can distinguish will vary a little depending on things like lighting conditions, the magazine says.
Meanwhile, in Fifty Shades of Grey news, a theater in Loveland, Colo., accidentally showed the beginning of the erotic thriller to an audience expecting the SpongeBob SquarePants movie earlier this week. "People ran out of there," a moviegoer tells the Denver Post. "You could hear little kids going, 'SpongeBob! SpongeBob!' as the parents were dragging them out." (Read more vision stories.)